A liquid crystal display device has advantages such as thinness, lightweight, low power consumption and so on, and is widely used in various technical fields such as computers, word processors, television sets, mobile phones, handheld terminal devices and so on. In addition, so-called touch panels of such liquid crystal display devices having a mechanics of manipulation by touch on their screen are spreading rapidly. The touch panels are widely used in mobile phones like smart phones, tablet computers, handheld terminal devices, automated teller machines, automatic vending machines, personal digital assistances, copying machines, facsimiles, game machines, guiding devices set up in facilities such as museums and department stores, car navigation systems, multifunctional terminals set up in convenience stores or monitoring devices of railroad vehicles.
The touch panel generally has a transparent electroconductive laminate comprising a transparent substrate on which a transparent electrically conductive layer is formed. Indium tin oxide is generally used to form a transparent electrically conducting layer.
A PET film or a polycarbonate film is commonly used as a substrate film of a transparent electroconductive laminate thanks to its high transparency and reasonable prices. A transparent hard coat layer can be preferably applied onto such a substrate film with a view to improving scratch resistance and durability. On the other hand, the application of a transparent hard coat layer onto a substrate causes a problem of the appearance of interference fringes. The appearance of interference fringes deteriorates visibility.
As for the appearance of interference fringes, the inventors et al., have already found a hard coating composition in the patent application No. JP 2012-079755 or JP 2012-079756, which solves the problem by providing a layer having a refractive index close to a refractive index of a polycarbonate substrate. The above two patent applications were unpublished applications at the time of filing the earlier application given as the basis for the priority. On the other hand, the hard coating composition in the above two patent applications has required further improvements.
Above-mentioned patent applications include phenylphenol acrylate that is comprised as a component of a hard coat layer. This component is a mono-functional component having a low molecular weight. The inventors assume that such a component may improve an adhesion to the polycarbonate substrate which is often used as a substrate by an etching erosion of the polycarbonate substrate. However, such phenylphenol acrylate is a mono-functional component having a low molecular weight. Thus, when a pyrolysis is generated, it may become a volatile component and it tends to inhibit a crystallization of the transparent conductive film formed on the hard coat layer (typically an ITO film). As a result, in the production of an electroconductive laminate, workability is lowered. Also, the phenylphenol acrylate component may improve an adhesion between the polycarbonate substrate and the hard coat layer by the etching erosion of the polycarbonate substrate as described-above. But, a higher level of an adhesion test (severe adhesion test) will generate a problem that a cohesive failure of the substrate surface is generated.